Radioactive waste disposal of water containing waste using urea-formaldehyde resin

ABSTRACT

A method of disposing of wet radioactive waste materials such as those generated in the water used to cool atomic reactors, comprising combining the waste material with a hydrophilic resin in proportions sufficient to provide a solid mass of the resin with the radioactive waste component distributed within. In its preferred form, the waste material is concentrated by separating water from the radioactive portions thereof by methods such as evaporation, taking up the waste components with an ion exchange resin and separating the resin from the bulk of the water, or by the addition of flocculating agents or the like and filtering. The preferred hydrophilic resinous material is a conventional urea-formaldehyde dispersion, which is partially polymerized and capable of taking up water and fully polymerizing upon the addition of an acidic curing agent. The method also contemplates adding a substantially waterproof resinous material to the surface of the solid block, or enclosing it in a waterproof container, or both.

This is a Continuation of application Ser. No. 220,449 filed Jan. 24,1972, and now abandoned.

BACKGROUND OF THE INVENTION

The present invention relates to improvements in RADIOACTIVE WASTEDISPOSAL, and more particularly to the disposal of radioactive materialsby immobilizing them within a solid mass for storage and/or burial.

It is well known that waste products occur as a natural result ofactivity involving the use of radioactive isotopes. For example, wasteproducts are provided during the operation of atomic reactors and thelike, and these waste products may be produced directly from primaryradiation sources or secondarily by the creation of isotopes fromnon-radioactive metals or the like. In order to assure smooth efficientcontinuation of atomic processes generating such waste material,efficient disposal means must be provided both for primary and secondarywaste products.

At the present time, disposal has been achieved by immobilizing thewaste in a solid block, and then by disposal at sea or by burial in aspecially designated burial site. Burial at sea requires more and morepreparation, because of the long range effects of certain pollutioncomponents that might build up. When the product is disposed of at aburial site, it is also necessary to provide safe means for transportingthe material to the burial site. In addition, it is important to assurethe containment and safe storage of the material at the burial site fora time sufficient to allow a sufficent decay of the radioactivecomponents to reduce the radiation intensity thereof to a relativelysafe level. Thus it is seen that whatever the disposal of the wastematerial, it is important to provide means for protecting the materialand assuring its safe storage at the disposal site for a long period oftime.

Prior to this invention, Portland Cement has been in rather widespreaduse for the purpose of encapsulating and holding radioactive wastematerial therewithin so as to provide a protective block for thematerial at the burial site. Portland cement has been found to beparticularly advantageous where the radioactive waste material ispresent in water, and it is advantageous to dispose of a certain amountof water along with the radioactive waste material in order to providean efficient handling process.

For example, the water utilized in the cooling loop of atomic reactorstends to accumulate contaminations of radioactive nickel and cobaltprobably as a result of conversion of iron and/or nickel in the tubescarrying the water. In any event, these materials build up in the waterso that it is important to remove the waste from time to time in orderto prevent a buildup from reaching a very hot or hazardous level. Insuch a case, probably the most serious component is cobalt 60, becauseit emits hard gamma rays and has a half-life of approximately fiveyears.

Prior to this invention, the cooling water was removed and mixed withPortland Cement in the usual water-cement ratio, allowed to solidify andthen the block of cement buried in a waste dump. Such disposal has beengenerally satisfactory for many operations, but it has a number ofdisadvantages. One of the disadvantages resides in the heavy weight ofthe cement and the like, which must be transported often over aconsiderable distance. Another disadvantage, and perhaps a more seriousone, resides in the fact that many waste products of this general classnow contain levels of boron material that render disposal in PortlandCement unsatisfactory or impossible because of the lack of compatabilityof the materials. Other areas of improvement are also seen to beavailable, such as the handling problems occuring with cement inprocessing equipment and the possibility of the cement setting up in anundesired fashion during an unexpected shutdown. Rather than go into allof the disadvantages of the cement process, it is proposed to provide animproved process in which certain advantages are achieved, and which isparticularly suitable for disposing of waste products having highconcentrations of compounds containing boron.

Another problem which has been of some concern with the use of PortlandCement is the possibility of the radioactive material leachingtherefrom. This problem is particularly acute where disposal at sea iscontemplated, and efforts to utilize materials other than PortlandCement have generally been in the area of the use of hydrophobicmaterials so as to render the solid block substantially leach-proof.However, the use of hydrophobic materials such as bitumen or asphalt hasa number of disadvantages particularly in the mixing and processingsteps, and the use of these materials has generally been rejected as notsubstantially improving the situation involved with the use of PortlandCement.

SUMMARY OF THE INVENTION

From the above background material, it is seen that a primary object ofthe present invention is to provide a process for making a disposablewaste product material in which improvements are made over the use ofPortland Cement in order to increase the range of disposable materials,provide reduction of weight required for shipping, and generally providea more reliable disposal from the standpoint of safety and the like.

These and other objects are achieved by solidifying the wet orwater-carried waste product through the steps of adding a hydrophilicresinous material to the waste in an amount sufficient to set up andcure into a solid block, mixing the materials together to provide thedesired distribution of waste materials therein, and curing the materialto a solid mass.

In general, it is believed that any hydrophilic resinous materialcapable of taking up water upon curing will be suitable to render thewetted or water-carried waste material immobile and shieldedtherewithin. However, the preferred hydrophilic resin is any of theusual urea-formaldehyde compositions, which are available commerciallyin the partially polymerized state, and capable of curing to a highpolymer upon the addition of an acidic curing agent. After theradioactive waste material is thus immobilized within a solid block ofhydrophilic resinous material, it may be waterproofed to protect againstleaching, if desired. This objective may be achieved by the addition ofa substantially waterproof resin as a coating thereover, or by a coveror any other protective waterproofing material that will preventtransfer of water from within to the outside and reverse.

Another object of the present invention is to provide improvementswithin this general process of providing a safe immobilized wasteproduct, and to increase the efficiency of the use of materials and thelike used up in the process.

Thus in the preferred form of the invention, the radioactive wastematerial is first concentrated to a level more suitable for disposal,but still at a sufficiently low level so as to remain within the lowhazard classifications. Where the radioactive material is present inwater, this concentration is obtained by water removal. In the case ofremoval of radioactive waste from the water in the cooling loop of areactor, the removed water may advantageously be returned to usage forfurther cooling.

In such a case, water containing radioactive ions such as radioactiveiron, nickel, and cobalt, are brought in contact with ion exchange resinbeads capable of taking up such cations and holding them within theresin mass. The water which is thus deionized and thereby has itsradioactive metallic ion component substantially removed is returned tothe cooling loop, and the wet resin beads containing the radioactivecomponents are then disposed of by encapsulating them within ahydrophilic resinous material as explained above, In general, any ionexchange resin capable of picking up radioactive waste components may beused. However, where it is desired to remove iron, nickel and cobaltions, cation exchangers should be used. Cation exchange resins are wellknown, and available commercially. A typical ion exchange resinpreferred in the practice of the process of this invention has astyrene-divinylbenzene matrix which is suitably sulfonated to provide astrongly acidic, cation exchange resin in the form of beads. Such resinsare sufficiently dense and insoluble in water to provide easyseparation, yet are sufficiently hydrophilic to provide the desired ionexchange activity as well as to provide compatability with thehydrophilic resins utilized in accordance with the present invention.

It will be appreciated that absorbing agents in general, which may ormay not be classified as ion exchange resins, but which are capable ofpicking up the desired radioactive component are also suitable. In thisconnection, materials such as diatomaceous earth, Powdex (powderedfilter aid) Solco Foc (wood cellulose flour) and the like are suitable.In such case, the substances may be filtered out advantageously toprovide solids having concentrates of wastes therein. When a typical ionexchange resin is used, instead of filtering same, the resin may beregenerated after separation in a more concentrated solution and theregenerated resin beads recycled for reuse. Another method ofconcentrating the materials is simply by vacuum evaporation of thewater, and the water vapor may be condensed and returned again to theprocess from whence it came, if desired.

While it will be seen that any of these methods for concentrating thewaste materials may be suitable in and of themselves, it is alsosometimes advantageous to provide a combination of methods so as toprovide a controlled concentration of waste and water in properproportion for mixture with the resin. In addition, filter aids andfiltration may be utilized instead of ion exchange beads to concentratethe materials and locate them in certain desired areas within the finalsolid resinous block. It is also desirable to add filler material or thelike to extend the resin and also act as an additional shield for theradioactive components.

In other words, the solids of this invention not only hold andimmobilize the waste material, but they provide a primary shieldtherefor so that the radiation such as hard gamma rays are reducedbefore leaving the solid mass in which the radioactive sources arecontained. It will also be appreciated that any other suitable fillermaterial may be added to the resinous components in accordance withthose materials suggested in the literature for use with the particularresin involved. In all such cases, the amount of filler will bedetermined by conventional standards, i.e. the amount which will bestextend and increase the use of the resin itself, but will stay withinthe ranges of physical properties desired for the final composition.

The use of hydrophilic resins in accordance with the present inventionis particularly advantageous with regard to handling of water solutionsand wet materials. Such handling not only has the advantage of allowingwater to be utilized as a carrier for pumping and other handling and thelike, but it also provides the build-up advantages of having waterpresent during the exothermic polymerization reaction. Duringpolymerization, the high heat capacity of the water prevents undue heatbuilt up and provides for proper curing without thermal breakdown. Inaddition, it provides a convenient method for getting rid of water thatmay contain waste in and of itself either as a primary carrier, or as acleaner utilized to flush out radioactive material from the system.

It has also been found that Portland Cement and hydrophilic resinousmaterials do not hold the water and associated ions in a sufficientlystrong bond for certain disposal applications, such as disposal at sea.In such cases, it is contemplated that the solid mass will be furtherencapsulated in one or more waterproof materials. For example, the solidwaste block may be advantageously prepared in a metal container such asa drum and the metal container disposed of along with the resin andwaste product. In such a case, however, the metal container maydisintegrate or corrode away and expose the resin block too quickly,particularly when subjected to corrosive action of sea water.Accordingly, it is preferred to coat and capsulate or otherwise coverthe hydrophilic resin block containing the waste material therein. Inother words, a substantially waterproof or water impervious resinousmaterial in the form of a coating or a bag or any other device that willassure containment may be used. If desired, such further material may becarried in a metal container.

For example, the process of this invention may be practiced by utilizinga large metal container such as a drum, lining the container with apolyethylene bag material, with the sides extending sufficiently toprovide a fold-over enclosure. With the procedure, the radioactive wastematerial, resin components, and any other of the materials suggested foruse in accordance with the process of this invention are then added, andthe resin cured to provide a solid block within the plastic bag and heldwithin the container. The bag is then folded over the top and sealed toprovide a waterproof coating, and the metal container is then closed.Where such a container is used, leaching of the waste materials will notoccur even after the metal container has corroded away.

Alternative to the bag process, it may be advantageous to utilize resinsthat will adhere to the hydrophilic resin utilized in the primaryprocess. Such processes may be carried out by first curing a base liningin the bottom of the container, then curing the plastic mass within thecontainer, with curing providing a certain amount of shrinkage, and thencuring the waterproof or water repellent resin in the further stagearound the side and top so as to completely fill the container andprovide a water resistant protective layer. For example, when thepreferred urea-formaldehyde resin is used for solidifying and retainingthe radioactive waste material in accordance with this invention, thewater resistant material may be a butylated urea-formaldehyde or amelamine-formaldehyde resin. These resins have improved resistance to aleaching effect of water. Alternatively, a typical hydrophobic resinousmaterial may be utilized instead of, but in the same manner, by using anasphaltic or bituminous material first as a layer on the bottom and thento fill the side and top voids after processing and shrinking.

Further alternatives and advantages of the invention will becomeapparent as the specification progresses and the new and useful featuresof the radioactive disposal described herein will be more fully definedin the claims attached hereto.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred hydrophilic resin to be used in accordance with thisinvention is any of the urea-formaldehyde resins available from aplurality of commercial sources as standard articles of commerce. Theseresins are prepared by reacting urea and formaldehyde in mol ratiosbetween about 1:1 and 1:4 respectively, and preferably between 1:1.5 and1:2.5. For optimum results, the mol ratio is about 1 part urea to about2 parts formaldehyde. Typically, solid urea and an aqueous solution offormaldehyde are reacted with one another to produce a resin syrup thatis in the thermosetting state but capable of being converted to athermoset state. These resins are available in syrup form, and sometimesavailable in a spray-dried form, which may be redispersed in water to adesired solids content. Since part of the water will come from the wastematerial, the urea-formaldehyde should be in a concentrated form withthe final ratio of resin solids and water being present in the finaldispersion in a ratio of about 21/2 to about 5 parts water per partresin by weight and preferably from about three to about 4 parts waterper part resin solids.

A typical catalytic material used to convert the urea resin to athermoset state at ambient temperature is an acidic material having adissociation constant between about 10⁰ to 10⁻ ⁵. The amount ofcatalytic material used will depend upon the strength of the acidicmaterial used and upon the nature of the composition in which it isused. For example, materials like boric acid tend to inhibit thepolymerization, and therefore increased catalyst is required to achievethe same cure time. However, generally the amount of acidic catalyticmaterial will be between say about 0.3 and 20% by weight of the resinsolids in the mixture. In general, any acid capable of providing a pHbelow 5 in the dispersion may be utilized, as is well known in the art,and it is preferred to utilize sodium bisulfate, since it is availableas a solid and provides an excellent strength acid.

Certain materials such as filter aids, ion exchange resins and materialsthat act as one of these or both are usually added in order to improveprocessing and provide the most economical and practical way toeliminate waste. However, any of these materials which are compatiblewith the urea-formaldehyde are suitable, and considerable latitude ispermissible in this area.

In order to illustrate the preferred procedures of the presentinvention, the following examples are set forth. However, it should beunderstood that these examples are primarily for the purpose ofillustration and any enumeration of detail contained therein should notbe construed as a limitation.

EXAMPLE 1

Water from a reactor cooling loop containing radioactive isotopes of theiron family is passed through a conduit packed with 1200 mililiters ofresin beads, which beads are composed of a cation exchange resinavailable commercially (specifically a sulfonated styrene-divinylbenzenepolymer). In this way, radioactive cationic materials are removed fromthe water and collected by the resin beads. The water is allowed todrain from the beads and the wet beads are then placed in a five galloncontainer. A 2000 ml solution or dispersion of urea-formaldehyde resinis then prepared by adding 1200 ml water to 800 ml of a dispersioncontaining about 63-66% solids. This diluted dispersion is then added tothe wet beads in the container, and the mixture stirred by an electricstirrer at a speed sufficient to keep the resin beads substantiallyevenly distributed in the mixture. 50 ml of a saturated solution ofsodium bisulphate is then added gradually with the stirring beingcontinued. After the sodium bisulfate is added and the mixture gelssufficiently to hold the resin beads from sinking by gravity, thestirring is discontinued and the stirring blades disconnected and leftin the mixture. The gel is then allowed to set until the cure iscomplete, whereupon the unit is ready for disposal.

EXAMPLE 2

Water from a reactor cooling loop containing radioactive waste is mixedwith 1200 ml of powdered ion exchange filter aid available in the tradeas Powdex. The Powdex is then filtered and added to a 5 galloncontainer. A 1200 ml solution or dispersion of urea-formaldehyde resinis then prepared by adding 900 ml water to 300 ml of a dispersioncontaining about 63-66% solids, and the urea-formaldehyde dispersionadded to the five gallon container. The mixture is stirred by anelectric stirrer, and 150 ml of a saturated solution of sodium bisulfateis added while continuing the stirring. After the solution gels, thestirring is discontinued and the mixture allowed to cure into a solidthermoset mass.

EXAMPLE 3

Water from a reactor cooling loop containing radioactive waste is mixedwith 1200 ml diatomaceous earth, and the diatomaceous earth removed byfiltration. 1200 ml of urea-formaldehyde dispersion similar to that usedin Example 2, and the treated diatomaceous earth is added to a fivegallon container. These materials are stirred with an electric stirrerand 100 ml of a saturated solution of sodium sulphate is added. Afterthe solution gels, the stirring is discontinued and the mixture allowedto cure into a solid thermoset mass.

EXAMPLE 4

Water from a reactor cooling loop containing radioactive waste is placedin a vacuum and about 80% of the water removed by vacuum evaporation.900 ml of the evaporated waste water and 1200 ml of a wood celuloseflour is added to a five gallon container. 300 ml of a urea-formaldehydedispersion containing about 63-65% solids is also added. The ingredientsare then stirred with an electric stirrer and 150 ml of saturated sodiumbisulfate is added. After the solution gels the stirring is discontinuedand the mixture is allowed to cure into a solid theremoset mass.

EXAMPLE 5

The procedure of Example 4 is repeated, except that the evaporated wastewater contains borate moities in the amount of about 20% by weight ofthe solution calculated as boric acid. Similarly good results areobtained.

EXAMPLE 6

Water from a reactor cooling loop containing radioactive waste isflashed in a vacuum to remove about 80% of the water. Another portion ofwater from the reactor cooling loop is passed through a conduit packedwith 1200 ml of ion exchange resin beads similar to those of Example 1.1200 ml of the evaporated water, the ion exchange resin beads, and 800ml of a urea-formaldehyde dispersion containing about 63-65% solids aremixed together by an electric stirrer and 50 ml of a saturated solutionof sodium bisulphate is added. After the solution gels, the stirring isdiscontinued and the mixture is allowed to cure into a solid thermostatmass.

The samples obtained from the procedures set forth above are comparedwith similar samples made with Portland Cement. In all cases, thesamples made with the urea-formaldehyde were as good as or better thanthose made with Portland Cement. Of particular note, is the fact thatcertain of the cement samples did not set at all. Moreover, contact ofthe other cement samples with sea water caused them to crack, while theresin samples remained intact under similar circumstances.

From the foregoing description, it is seen that there has been providedan improved method of disposal of radioactive waste material, andparticularly an improvement over the process using cement heretofore inmajor usage.

We claim:
 1. The method of solidifying radioactive waste materialcontaining free water into a free standing body, comprising:A. providinga mixture of radioactive waste material and water in a controlled amountsufficient to meet a desired low hazard radiation classification whensolidified with urea-formaldehyde and urea-formaldehyde in a partiallypolymerized state in an amount sufficient to solidify substantially allof the water present, B. adding an acidic curing agent capable ofpromoting polymerization of said urea-formaldehyde in an amountsufficient to solidify said urea-formaldehyde in said mixture, and C.stirring the materials together to provide the desired distribution ofradioactive waste material and allowing the mixture to gel and setwhereby a solid mass of the resin is obtained with the water and theradioactive components of the resulting mixture distributed therein. 2.The method described in claim 1 wherein said acidic curing agent is anacidic material having a dissociation constant between about 10° and 10⁻⁵.
 3. The method described in claim 2 and wherein said curing agent is awater solution of sodium bisulphate.
 4. The method described in claim 1and wherein the urea-formaldehyde comprises a resin syrup of partiallypolymerized urea-formaldeyde in water.
 5. The process of claim 1 inwhich the radioactive waste material is obtained from radioactivecooling water for atomic reactors by removing water to concentrate thewaste material.
 6. The process of claim 1 in which the radioactive wastematerial is a high intensity waste obtained as a slurry by taking up theradioactive waste from cooling water for atomic reactors by using aninsoluble absorbent agent and removing a portion of the water from theslurry.
 7. A process of claim 6, in which the insoluble absorbent agentis an ion exchange resin.
 8. A method of disposing of radioactive wasteas defined in claim 1, in which a filler material is added to extend theurea-formaldehyde and provide additional shielding.
 9. A method ofprocessing wet radioactive waste material for safe disposal comprisingthe steps of:A. placing the wet waste material in an imperviousnoncorrosive container, B. providing a mixture of the wet radioactivewaste material and water in a controlled amount sufficient to meet adesired low hazard radiation classification when solidified withurea-formaldehyde, C. adding urea-formaldehyde in a partiallypolymerized state in an amount sufficient to solidify substantially allof the water present, D. mixing the wet waste material andurea-formaldehyde to provide a body of urea-formaldehyde with wastematerial dispersed therein, E. adding an acidic curing agent to themixture in an amount capable of promoting polymerization of saidurea-formaldehyde in said mixture, F. stirring the materials together toprovide the desired distribution of radioactive waste material andallowing the mixture to gel and set whereby a solid mass of the resin isobtained with the water and the radioactive components of the resultingmixture distributed therein, and G. sealing said impervious noncorrosivecontainer to thereby prevent leaching of said solid resinous substance.10. A method of disposing of radioactive waste carried in water, thesteps of:A. placing the water and waste material in a plastic bag, B.providing a mixture of the water and waste material in a controlledamount sufficient to meet a desired low hazard radiation classificationwhen solidified with urea-formaldehyde. C. adding a urea-formaldehyderesin in a partially polymerized state in an amount such that the waterpresent in the mixture and in the urea-formaldehyde resin added wouldform a dispersion of from about 20 to about 40% by weight of said resinbased on the resin solids content of the combined weight of said resinand water present, and said amount being sufficient to solidifysubstantially all of the water present, D. mixing the componentstogether to disperse the waste throughout said resin, E. adding anacidic material in an amount sufficient to solidify saidurea-formaldehyde in said mixture and having a dissociation constantbetween about 10° and 10⁻ ⁵, F. stirring the materials together toprovide the desired distribution of radioactive waste material andallowing the mixture to gel and set whereby a solid mass of the resin isobtained with the water and the radioactive components of the resultingmixture distributed therein, and G. folding the top of said plastic bagand sealing said plastic bag to thereby prevent leaching of said waste.11. The process of claim 10 in which the radioactive waste material isobtained from radioactive cooling water for atomic reactors by removingwater to concentrate said radioactive waste.
 12. The process of claim 10in which the radioactive waste material has high intensity radiationcomponents obtained as a slurry by taking up the radioactive waste fromcooling water for atomic reactors by using an insoluble adsorbent agentand removing a portion of the water from the slurry.
 13. A process ofclaim 12, in which the insoluble absorbent agent is an ion exchangeresin.
 14. A method of disposing of radioactive isotopes dispersed ordissolved in water, comprising the steps of:A. providing a mixture ofradioactive isotopes and water in a controlled amount sufficient to meeta desired low hazard radiation classification when solidified withurea-formaldehyde, B. admixing the water and radioactive isotopes withurea-formaldehyde resin in a partially polymerized state with theproportions of urea-formaldehyde resin and water in the mixture beingfrom about 20 to about 40% by weight of said resin based on the resinsolids content of the combined weight of said resin and water present,said amount being sufficient to solidify substantially all of the waterpresent, C. mixing the components together, D. adding an acidic materialhaving a dissociation constant between about 10° to 10⁻ ⁵ and in anamount sufficient to solidify said urea-formaldehyde in said mixture andE. stirring the materials together to provide the desired distributionof radioactive isotopes and allowing the mixture to gel and set wherebya solid mass of the resin is obtained with the water and the radioactiveisotopes of the resulting mixture distributed therein, and F. coatingthe solid mass thus formed with a water impervious resinous material.15. A method of disposing of radioactive isotopes in the form ofmetallic ions carried as waste material in water, comprising the stepsof:A. adding particles of an ion exchange resin to the water for a timesufficient to take up the radioactive metal ions in the water, B.removing the particles of an ion exchange resin from the water, C.providing a mixture of the ion exchange resin particles and water in acontrolled amount sufficient to meet a desired low hazard radiationclassification when solidified with urea-formaldehyde, D. then addingthe ion exchange resin particles to an aqueous dispersion ofurea-formaldehyde resin, with the proportions of urea-formaldehyde resinand water present in the mixture being such that a dispersion of saidurea-formaldehyde resin and the water present would contain from about20 to about 40% by weight of said urea-formaldehyde resin based on theresin solids content of the combined weight of said urea-formaldehyderesin and water present, and the amount of urea-formaldehyde beingsufficient to solidify substantially all of the water present, E. mixingthe components together to provide a desired dispersion of waste withinthe urea-formaldehyde. F. adding an acidic material having adissociation constant between about 10° and 10⁻ ⁵ and in an amountsufficient to solidify said urea-formaldehyde in said mixture, G.stirring the materials together to provide the desired distribution ofsaid ion exchange resin particles and allowing the mixture to gel andset whereby a solid mass of the resin is obtained with the water and theradioactive components of the resulting mixture distributed therein. 16.A method of disposing of radioactive isotopes carried as waste materialin water, comprising the steps of:A. evaporating a portion of the waterto concentrate the waste material therein, B. thereby providing amixture of radioactive waste material and water in a controlled amountsufficient to meet a desired low hazard radiation classification whensolidified with urea-formaldehyde, C. adding an aqueous dispersion ofurea-formaldehyde resin to the concentrated waste, with the proportionsof urea-formaldehyde resin and water present in the mixture being suchthat a dispersion of said resin and the water present could contain fromabout 20 to about 40% by weight of said resin based on the resin solidscontent of the combined weight of said resin and water present, and theamount of urea-formaldehyde being sufficient to solidify substantiallyall of the water present, D. mixing the components together, and E.adding an acidic material having a dissociation constant between about10° and 10⁻ ⁵ and in an amount sufficient to solidify saidurea-formaldehyde in said mixture, and F. continuously stirring theresulting mixture to provide the desired distribution of waste materialand until the mixture gels and allowing the gel to set whereby a solidmass of the resin is obtained with the water and the radioactivecomponents of the resulting mixture distributed therein.
 17. A method ofdisposing of radioactive isotope waste as defined in claim 16, in whicha filler material is added to extend the resin and provide additionalshielding.
 18. A method of disposing of radioactive isotope waste asdefined in claim 16, in which the radioactive isotopes include cobalt60.
 19. A method of disposing of radioactive isotopes in the form ofcationic waste material in water, comprising the following steps in theorder given:A. taking a first portion of carrier water and includedwaste material and bringing said portion into contact with ion exchangeresin particles activated to take up cations for a time sufficient totake up substantially all of said cationic waste material, and removingthe thus treated ion exchange resin particles from the major portion ofthe water, B. taking a second portion of carrier water and includedwaste material and concentrating said second portion by evaporatingwater therefrom, combining the treated resin particles and saidconcentrated second portion with a partially polymerizedurea-formaldehyde resin, the proportions of said mixture being adjustedto provide a mixture sufficient to meet a desired low hazard radiationclassification, and in which the portions of urea-formaldehyde resin andwater present in the mixture are such that a dispersion of saidurea-formaldehyde resin and the water present would contain from about20 to about 40% by weight of said urea-formaldehyde resin based on theresin solids content of the combined weight of said urea-formaldehyderesin and water present, said amount being sufficient to solidifysubstantially all of the water present in said mixture, C. and adding anacidic material in an amount sufficient to solidify saidurea-formaldehyde in said mixture and having a dissociation constantbetween about 10° and 10⁻ ⁵ to the mixture, D. and stirring thematerials together to provide the desired distribution of radioactivewaste material and allowing the mixture to gel and set whereby a solidmass of the resin is obtained with the water and cationic waste materialof the resulting mixture distributed therein.
 20. A method of disposingof radioactive isotopes as defined in claim 19, in which the radioactiveisotopes include cobalt
 60. 21. A method of disposing of radioactiveisotopes as defined in claim 19, in which the proportions ofurea-formaldehyde resin and water present in the mixture are such that adispersion of said urea-formaldehyde resin and water present wouldcontain from about 25 to about 35% by weight of said urea-formaldehyderesin based on the resin solids content of the combined weight of saidurea-formaldehyde resin and water present.